Packing for centrifugal pumps



Nov. 28, 1933. c. A. SCHELLENS PACKING- FOR GENTRIFUGAL PUMPS 5Sheets-Sheet 1 Filed Jan. 31, 1930 INVE TOR A TTORNEYS Nov. 28, 1933. c.A. SCHELLENS PACKING FOR CENTRIFUGAL PUMPS Filed Jan. 31, 1930 3Sheets-Sheet 2 ATTORNEW NQV. 28, 1933. A SCHELLENS 1,936,771

PACKING FOR CENTRIFUGAL PUMPS Filed Jan. 31 1930 5 Sheets-Sheet 3 aINVENTOR +44.0 ATTORNEYS Patented Nov. 28, 1933 PATENT OFFICE PACKINGFOR CENTRIFUGAL PUMPS Christopher a. Schellens, Marblehead, Mass,assignor to -8 Engineering Company, Englewood, N. J., a corporation ofDelaware Application January 31, 1930. Serial No. 424,752

8 Claims. (01. 286-9) This invention relates to centrifugal pumps andparticularly to improvements in packing or sealing means for such pumps.

The invention is especially useful in connection with high speed pumps,such as disclosed in my Patent No. 1,664,488, issued April 3, 1928.

In pumps of this character difficulties are encountered from leakage; Itis'especially difficult to overcome leakage at the inlet'side of suchpumps owing to the overhung or outboard arrangement of the impellers.The primary object of my invention is to overcome these difliculties,More specifically stated, it is an object of my invention to provideeffective sealing means in pumps of the character described whereby highpressure leakage is prevented.

Another object of my invention is to provide effective sealing meanshaving long life.

ordinary wear of the sealing portion will not destroy the effectivenessthereof.

How the foregoing, together with such other objects and advantages asmay hereinafter appear, or are incidentto my invention, are realized,

is illustrated in preferred form in the accom-' .panying drawings,wherein-- Fig. 1 is a section through a pump constructed so inaccordance with my'invention with certain of the parts appearing inelevation;

Fig. 2 is an enlarged view showing the runner.

- partly in elevation and partly in section; and illustrating myimproved sealing means in asso- 5 ciation therewith.

Fig. 3 is a face view of a sealing ring.

Fig. 4 is a fragmentary view of a modification of the sealing ringillustrated in Figs. lto 3 inclusive.

In the drawings, the pump A, in general, comprises a casing 4 having awater inlet 5 to the pump bowl 6, around which there is the dischargechamber '1 having an outlet 8 for connection to a' boiler or thelike;and a runner'or impeller B secured to the end of the drive shaft 9, theshaft being threaded into the face of therunner casting opposite theintake side and the runner having a hub 10 for this purpose. The shaft 9is supported by suitable bearing means 11 and may be driven by a highspeed motor, such as a high speed steam turbine motor.

It is to'be observed that the shaft 9 extends only partly into therunner B from the face opposite the intake side thereof which enables Afurther object of my invention is the pro- 'vision of sealing means ofsuch character that me to arrange the inlet ends of the fluid passages'on a small radius.

The runner B has anaxial intake and a radial discharge from itsperiphery. It has a plurality of water passages c terminating at theentrance or intake side in a plane perpendicular to the axis ofrotation, the intake ends of said passages being arranged in a circulargroup on a small radius around the central boss or crown 12. The wallsbetween the passages constitute cutting blades.

By employing such a runner having an inlet eye of small diameter, I amenabled to employ a correspondingly small diametered inlet throat ornozzle, and thus I am enabled to cut down the 7 amount of leakage verymaterially.

In the drawings the nozzle or throat is in the form of a floatingpackingmember 16 arranged to prevent leakagebecause of' the following provi-'sion. 7

Referring to Figs. 1 to 3, the packing member 76 16 is of ring-like .orcylindrical form and comprises a sleeve portion 17, an outer annularflange portion 18, and a web portion 19 connecting the sleeve and flangeportions. Theweb 19 is so 10-. so cated as to provide an inner annularrib 20 in the packing member. Stated in another way the packing member16 has an enlarged end portion provided with an inner annularrib orflange, an outer annular flange, and a connecting web. 5 The outerflange, rib, and web are so disposed and of such proportions asto-provide a cupshaped end for the member 16 having an inner flange orrib of less depth than its outer flange.

In other words the outer flange 18 overhangs the inner rib 20.

The sleeve portion 17 of the packing member slidably fits a ring 21secured in the inlet portion of the pump casing, and, therefore, thepacking member may shift axially. However, the packing member isprevented from rotating as by means of a pin 22 carried thereby andfitting an elongated groove 23 in the ring 21. Packing material 24 maybe provided in the ring 21.-

4 The enlarged end portion of the packing mem-. ber lies in the pressurespace of the pump bowl and the face 25 of the inner annular rib 20 isadapted for possible contact against the end face 26 of the impeller B.The outer annular flange 18, however, is disposed in surrounding andspaced relation to the end portion of the impeller.

In this connection it is pointed out that the impeller has a cylindricalaxial inlet portion 27 which, in this instance, is provided with aringlike nut 28 carrying the end face 26 above menequilibrium. o v i Itis pointed outthat when theouter diameter tioned. The outside diameterof the nut 28 at 29 is slightly smaller than the inside diameter of theannular flange 18 at 30, and, therefore, a small annular inlet 31 isprovided through which pressure fluid from the pump casing enters intothe annular chamber 32 located between th packing member 16 and theimpeller. I

In operation, the packing member 16 is held in equilibrium in a definiteaxial position relative to the impeller B in the following manner.Assume, first, that the packing member is in a po- .sition in whichaxial forces acting on it are bazanced. Next imagine it to be moved awayfrom the impeller by some external force. It is appar ent that in suchposition the fluid pressure in the chamber 32 will be reduced, since theoutlet from the chamber, namely, the clearance between the face 25 ofthe rib 20 and the face 26 of the impeller, has been increased, whilethe inlet 31 to the chamber 32 ,hasremained the same. Duetogthisdecrea'sed fluid pressure, the. packing rnem her will tend to beforced, back toits position 2001. of the rib 20 is substantially equalto the outer diameter 17a of the sleeve 17, asillustrated in Figs. 1 and2, the packing member 16 will be in equilibrium when in substantialcontactwith the memberf28 of the impeller, and with substantially noleakage taking place between them. However, I also contemplate makingthe diameter 20a larger than the diameter 17a in which case the packingmember 16 will rest against the member 28 with a bearing pressuredetermined by the difference in diameters-the larger the diameter 20athe larger the bearing pressure with which the packing member restsagainst the member 28 of the impeller.

I further contemplate making the diameter 20a smaller than the diameter1711, as illustrated in Fig. 4, in which case the packing member 16 willassume a position in which the face 25 of the rib 20 will be removedfrom the face 26 of the member 28, and the smaller this diameter is justreferred to that the packing member will be removed from the impeller bya fine clearance, permitting of a small leakage, or film of fluidbetween them, I have found that satisfactory results may be obtainedwhen the packing member bears against the impeller with a lightpressure.

From the foregoing it will be seen that the packing device may be soproportioned as to permit of small leakage or substantially no leakageeven though the radial clearance 31 may be of substantial amount.

In Fig. 5 I have illustrated a modification in which the impeller B isprovided with an annular flange 28b, in this instance formed on themember 28a, which flange overhangs a flange 161) on the packing member16a, there being an annular clearance 31a between the adjacentcylindrical surfaces of the flanges 28b and 16b. The member 16a isprovided with an inner rib 16c and the arrangement of parts is such asto form a chamber 32a having annular inlet at 31a. The similaritybetween the forms shown in Figs. 2 and 5 is obvious and, therefore, theoperation of modification will be clear from the fore. going.

In Hg. 6 a modification is illustrated in which the packing member 16dis supported from the member is so proportionedas to be held againstimportant feature of invention, because with such an arrangement, wearof the end faces'of impeller, the impeller being provided with anut-like member 28c having a sleeveportion 2811 in which the packingmember is axially movable. A pin 28c working in a slot 28) causesrotation of the packing member with the impeller while permitting theaxial movement referred to.

The packing member in this instance is provided with a flange 16e havinga cut-away portion 16f and an end face 169, and the pump casing isprovided with a shouldered inlet bore 16h ha 'ing a face 162' andcylindrical surface 167'. The packing member is so associated with theinlet bore 16h that an annular clearance 31b is formed between thecylindrical surface 167' of the bore and that the end face 169 isarranged for possible contact with the face 162'. In this modification afluid'chamber is formed at 32b to which pressure fluid is admittedthrough the annular inlet or clearance 31b. The packing thefface 161' ofthe casingwith a light. bearing contact under the'influen T 'of fluidpre ures.

.The provision ofr the annular inlet orf-clearance betweencylindrical-surfaces constitutes'an the device'does not change-theannular clearance and, therefore, such wear does not alter therelationship of the pressures necessary to a proper functioning of thedevice, it being pointed out, for example, that the rib 20 may wearpractically back to the web 19 without disturbing the relationship ofpressures. The importance of this is easily understood when it isconsidered that even with the most rigid inspection, at the high speedsinvolved, it is very difiicult to have the impeller run exactly true. Ifthe initial concentricity is out very slightly, this will be greatlyexaggerated after the pump reaches a very high speed, resulting in wearof the packing member. 115 Through the practice of my invention suchwear is taken care of for a considerable period without disturbing theproper functioning of the packing device, which makes for a very longlife.

While I have only described the arrangement at the inlet end of theimpeller, it is to be understood that a similar arrangement may beemployed at the other end of the impeller as indicated at 34; Theoperation of the arrangement at 34 will be understood from the foregoingdescription. Any leakage at this inboard side of the impeller may bedrained off through a pipe 35.

What I claim is:

1. The combination with a rotatable member having a cylindrical endportion and a casing therefor, of a floating packing member guided inthe casing and operating to maintain a seal against high pressureleakage past the rotatable member, said packing member having an innerannular rib, an outer annular flange and a connecting web arranged toform a chamber having communication with high pressure fluid, the outerannular flange being in surrounding and spaced 14( relation to thecylindrical end portion of the rotatable member to afford suchcommunication and the face of the rib being adapted to coact with an endface of the rotatable member to form the aforesaid seal,

2. The combination with a casing and a rotatable member havingacircularendportion, of a ring-likefloating packing member associatedwith the rotatable member and, being guided in the casing, said packingmember having an en- 1150 larged end with an annular flange insurrounding and spaced relation to the circular end portion of therotatable member and having an inner annular rib pressure held away fromthe face of the circular end portion of the rotatable member by a smallclearance through the medium of pressure fluid admitted through theannular space between the annular flange of the packing member and thecircular end portion of the rotatable member.- v

3. The combination with a casing member and a rotatable member, of apacking member having a leak restraining connection with one of saidmembers permitting axial motion relative thereto, saidpacking member andone of the other members having cooperating faces adapted forsubstantial contact under the influence of fluid pressures, and a fluidpassage for applying fluid pressurp formed by a cylindrical surface ofthe packing member spaced from a cylindrical surface of one of the othermembers.

4. In a pressure fluid device having a casing with an axial fluid inletand a discharge chamher, and an axial inlet peripheral discharge rotaryimpeller receiving fluid from said inlet and delivering fluid to saiddischarge chamber, the combination of a member axially movable by fluidpressures to maintain a seal against leakage from said discharge chamberto the inlet side of the impeller, said member having a portion adaptedto cooperate with an adjacent part to provide a chamber havingcommunication with said discharge chamber, and an annular space betweentwo cylindrical surfaces affording such communication.

5. In a pressure fluid device having a casing with an axial fluid inletand a discharge chamber, and an axial'inlet peripheral discharge rotaryimpeller receiving fluid from said inlet and delivering fluid to saiddischarge chamber, the combination of an axially movable memberassociated with said fluid inlet and impeller, said member having anenlarged end portion provided with a cylindrical surface, an end face,and a recess; a face cooperating with said end face to provide a sealagainst leakage from the discharge chamber to the inlet side of theimpeller; a cylindrical surface cooperating with said first mentionedcylindrical surface to provide an annular passage, and

a chamber between said seal and annular passage formed by said recess towhich fluid under pressure is led through the annular passage.

6. In a pressure fluid device having a casing with an axial fluid inletand a discharge chamber, and an axial inlet peripheral discharge rotaryimpeller receiving fluid from said inlet and delivering fluid to saiddischarge chamber, the combination of a member axially movable byv fluidpressures to maintain a seal against leakage from said discharge chamberto the inlet side of the impeller, said member having a raised surfaceproviding said seal, and having other portions cooperating with anadjacent part to provide a fluid chamber with a fixed inlet from theaforesaid discharge chamber.

7. The combination with a rotatable member and a chamber associatedtherewith, of an axially movable sleeve-like packing member having asurface adapted to be presented toward a face of an adjacent part toprovide a seal, said packing member also having portions cooperatingwith an adjacent part to provide a fluid pressure cham ber with an inletestablishing communication between the first mentioned chamber and fluidpressure chamber, the surfaces providing said inlet being non-contactingand so disposed with reference to the aforesaid faces which arepresented toward one another that wear of the latter does not alter thesize of said inlet, and said packing member also having surfacessubjected to pressure from the first-mentioned chamber and to pressurein said fluid pressure chamber proportioned to maintain the presentedfaces together under predetermined pressure.

8. The combination with a rotatable member and casing of a packingtherefor comprising a packing element cooperating with the rotatablemember and casing and having an inner annular rib, an outer annularflange, and a connecting web arranged to form a fluid chamber betweenthe rotatable member and packing element, said outer annular flangebeing spaced from the rotatable member to provide an annular inlet tosaid fluid chamber, and said inner annular rib being pressure heldremoved from the rotatable member by a small clearance.

CHRISTOPHER A. SCHELLENS.

